1. Field of the Invention
The present invention relates to a mobile robot, and more particularly to a position calculation system for a mobile robot and a charging-stand return system and method using the same, wherein, the position calculation system is capable of accurately calculating a position of a wireless signal source using a wireless signal, and the charging-stand return system is capable of allowing the mobile robot to accurately and rapidly return to the charging-stand using the calculated position.
2. Description of the Related Art
A robot, which has been developed as an industrial robot, has been used as a part of the factory automation. In addition, the robot has been used so as to collect or acquire required information as a substitute for a human being in an extreme situation which would be intolerable for a human being. With the application of the robots to the high-tech space development industry, a robotics field has more rapidly developed. Recently, the robotics field has developed a human-friendly domestic robot, and a representative example thereof is a cleaning robot.
A cleaning robot, which is a kind of a mobile robot, is an apparatus for freely moving around a defined cleaning area such as a house or an office, and inhaling dust or impurities. The cleaning robot includes components of a general vacuum cleaner as well as other components. Herein, said other components include a running apparatus for running the cleaning robot, a plurality of sensors for detecting collision of the cleaning robot so as to prevent the cleaning robot from colliding with various obstacles, and a microprocessor for controlling the above-mentioned components of the cleaning robot, etc. The cleaning robot provides power for driving through a battery since it moves freely in the cleaning area.
On the other hand, the cleaning robot has an auto-charging function in order for the convenience of a user. In accomplishing the auto-charging function, the cleaning robot checks the power level remaining in the battery. If the power level remaining in the battery is below a reference value, the cleaning robot automatically returns to a charging-stand which is placed at a predetermined position in the cleaning area, recharges the battery, and restarts a corresponding operation thereof.
However, the conventional charging-stand auto-return method for a cleaning robot is a method for attaching an artificial mark to the charging-stand, determining a position of the charging-stand when the cleaning robot detects the mark attached to the charging-stand through random running, and then allowing the cleaning robot to return to the charging-stand.
In addition, the conventional charging-stand auto-return method has problems that, in order to allow the cleaning robot to detect the artificial mark attached to the charging-stand, the charging-stand must be installed in the same area at which the cleaning robot is placed, and no obstacle between the cleaning robot and the charging-stand is present.
For example, in a case where the charging-stand is placed in a living room while the cleaning robot is placed in a different room, since the cleaning robot cannot detect the artificial mark attached to the charging-stand due to an obstacle such as a wall, it may not be possible to allow the cleaning robot to normally return to the charging-stand.